This invention relates to methods and apparatus for rapidly screening materials, and in particular to the combinatorial preparation and screening of diverse libraries of materials using transmission X-ray diffraction and other screening techniques.
One approach to the discovery of new materials involves the generation of large collections (libraries) of materials and the systematic screening of those collections for materials having a desired property. Given approximately 100 elements in the periodic table that can be used to make compositions consisting of two or more elements, an incredibly large number of possible new compounds remains largely unexplored. As such, there is a need for more efficient, economical and systematic approach for the synthesis of novel materials and for the screening of such materials for useful properties.
In general, combinatorial material science refers to methods for creating a collection of chemically diverse compounds or materials and to methods for rapidly testing or screening this library of compounds or materials for desirable characteristics or properties. The combinatorial technique, which was introduced to the pharmaceutical industry in the late 1980s, has dramatically sped up the drug discovery process. Recently, combinatorial techniques have been applied to the synthesis of inorganic materials. Using various surface deposition techniques, masking strategies or processing conditions, it is possible to generate hundreds or thousands of materials with distinct compositions per square inch in an array of elements which form a library. The materials generated using these combinatorial techniques have included high temperature superconductors, magnetoresistors, phosphors and pigments. The discovery of new catalysts should also benefit from these combinatorial techniques. General combinatorial material science methodologies are disclosed, for example, in U.S. Pat. No. 5,776,359, which is incorporated by reference herein.
Once these libraries of hundreds or thousands of new potential materials have been generated, they must be screened for performance characteristics or properties. The potentially vast number of materials to be screened, combined with the often low concentration of components in each library member, places a premium on the need for rapid screening techniques that are able accurately to measure properties at low concentration levels.
In many cases, it can be desirable to screen materials libraries using two or more different screening techniques. Depending on the particular properties to be measured, screening techniques that can be useful in this context may include x-ray diffraction analysis, Raman spectroscopy, infrared spectroscopy, ultraviolet spectroscopy, thermal imaging, electron microscopy, optical microscopy, polarimetry, fluorometry, as well as other known techniques. Examples of the application of such techniques are described in U.S. Pat. Nos. 6,157,449, 6,371,640, 6,373,570, 6,536,944, and U.S. Patent Application Publication No. US2003/0124028, all of which are incorporated by reference herein. However, the application of multiple screens can greatly extend the amount of time required to characterize libraries of materials, particularly as the number of materials grows large. And where material or sample transfer and/or manual handling of the materials is necessary to prepare the materials for each different screen—for example, when different screening techniques have different structural or environmental requirements—the time required to completely screen a large library can grow even more.